GALLIUM COLLOID FORMATION DURING ION-IMPLANTATION OF GLASS

Data are reported on the size and depth distribution of gallium colloi ds formed by gallium ion implantation at energies of 50 and 60 keV, an d nominal doses up to 1.1 X 10(17) ions/cm(2) into coverslip glass, fl oat glass and white crown glass. Measurement techniques used to reveal colloid-induced changes include the wavelength dependence of optical reflectivity, transmission electron microscopy (TEM) and Rutherford ba ckscattering (RES). The reflectivity can be controlled by variations i n ion dose, implant temperature and ion beam energy. The highest refle ctivity is found after implants near 50 degrees C and the level is ext remely sensitive to the implant temperature. For controlled beam condi tions, the reflectivity data are reproducible, despite there being var iations in the colloid size and depth distributions as seen by TEM and RES. The TEM data reveal that the depth distribution develops in two distinct regions, which at high concentration can precipitate into two layers of large colloids. Subsidiary experiments are reported to atte mpt to separate the effects of variations in the implant temperature a nd surface charging which influence the reflectivity, RES and colloid formation.